Air cooling means for free piston engines



Feb. 3, 1948. G. A. MUELLER, JR. ETAL 14 3 I AIR COOLING MEANS FOR FREEPIST ON ENGINES Filed Aug. 20, 1945 2 Sheets-Sheet l INVENTORQ George A.Mus/k5]:

ATTORNEYQS Feb. 3, 1948.

e. A. MUELLER, JR.', arm, AIR COOLINQ MEANS FOR FREE PISTON ENGINES 2she tssheet z Filed Aug. 20, 1945 INVENTOR George 4. Mud/end} Paul 66/7/r'/e I Patented Feb. 3, 1948 AIR COOLING MEANS FOR FREE PISTONENGINES George A. Mueller, Jr.,

Hamilton, Ohio,

assignors, ments, to Lima-Hamilton York, N. Y., a corporation of andPaul 8. Shirley,

by mesne assign- Corporation, New Virginia Application August 20, 1945,Serial No. 611,498 9 Claims. (Cl. 123-46) This invention relates tointernal combustion engines of the free piston type, and particularly tocooling means for the power cylinders therof.

An object of the invention i the provision of simple and efficientmeans, made effective by running of the engine, for circulating acooling fluid, preferably air, in a confined space around the combustionchamber lining and lengthwise thereof.

Another object of the invention is the provision of simple cooling meansin connection with the power cylinder lining of an internal combustionfree piston engine whereby the compressor pistons on an outstroke createa vacuum in a space around said liner to cause air under at leastatmospheric pressure to flow therein, and on an instroke to cause suchair to flow lengthwise of the liner and exhaust from said space attheopposite end of the liner to the air intake.

Further objects and advantages of the invention will be apparent fromthe following detailed description and from the accompanying drawings,in which Fig. 1 is a central longitudinal section of an ing of aninternal combustion free piston engine interiorly of which is providedthe customary combustion chamber 2 and at each end thereof cylinders 3and 4 forming the respective air compressor chamber 5 and bounce chamber6, with the chambers 2 and 6 of substantially the same diameter and withthe chamber 5 of larger diameter. Two oppos ng piston sets are provided,each including pistons 1, 8 and 9 working, respectively, in the chambers2, 5 and 6 and operating in a manner well understood in the art. Asynchronizing connection between the piston sets causes them to haveopposed movements in unison and includes a rack-bar l projectinginwardly from each compressor piston 8 through an airtight guide openingin the inner end wall of the cylinder 3 and connected with the otherrackbar through an interposed pinion Ii, as is common in the art. Therack portions of the bars are at the outer sides of the guides.

Fuel is injected into the combustion chamber 2 through a centrallydisposed nozzle i2 and ex-- haust from the chamber takes place through aconduit l3, while scavenging air is admitted to the chamber from aconduit l4 leading, in the present instance, from a scavenging receiveri5. This receiver has communication with both compressor chambersthrough ports "5 therein that are uncovered by the pistons 8 whensubstantially midway of their inward strokes.

The wall of the combustion or power chamber 2 is formed by a cylindricalliner 20 set within an outer cylinder2l in spaced concentric relationthereto to form a space 22 therebetween that is open at its oppositeends to the spaces 23 and 24 at the inner end portions of the respectivecylinders 3. In the present instance the parts 20 and 2| constituteseparate members, one inserted within the other, and spaced by suitablelugs or other parts projecting from one or the other. The spacing meansincludes nipple portions 25 forming exhaust and scavenging ports 26 and21, respectively, in the liner 20. The liner 20 is preferably formedwithin the passage 22 with a spiral rib or fin portion 28 restrictingthe passage and serving as a cooling fin for the liner in surroundingrelation to the combustion chamber 2.

Air is admitted, in the present instance. to the space 23 from theatmosphere through an inlet 29 having an inwardly opening valve 30therein and is exhausted to the atmosphere from the space '24 through anoutlet conduit 3| having an outwardly opening valve 32 therein. It isthus apparent that during an outstroke of the pistons a vacuum iscreated in the spaces 22, 23 and 24, causing air to rush therein throughthe inlet 29, and during an instroke of the pistons this air is causedto rush through the liner space 22 in the direction of the exhaust 3i,thus effecting an efiicient and continuous cooling of the combustionchamber wall. unidirectional flow of cooling air along the powercylinder liner, so that an eflicient use of the air stream for coolingis obtained.

Air is admitted to thecompressor' chambers 5 through respective inletpassages 35 and inward, ly opening valves 36 and is discharged from suchchambers to a receiver 31 through outwardly opening valves 38 andconduits 39. Nothing new is claimed for this.

We wish it understood that our invention is not limited to any specificconstruction, arrangement or form of th parts, as it is capable ofnumerous modifications and changes without departing from the spirit ofthe claims.

Having thus described our invention, what we claim as new. and desire tosecure by United States Letters Patent, is:

1. In an internal combustion free piston engine having a power cylinderliner, compressor pistons at opposite ends of the liner, and spaces atthe inner sides of said pistons, means providing communication betweensaid spaces in close relation to said liner, one of said spaces having avalved inlet for low pressure air and the other a valved outlet awayfrom said communication, whereby air is drawn into said spaces and saidcommunication through said inlet on an outstroke of the pistons and isforced therefrom and through said outlet on an instroke of the pistonsto effect cooling of the liner. Y

2. In an internal combustion free piston en- This action maintains agine having a power cylinder liner, compressor pistons at opposite endsof the liner, and spaces at the inner sides of said pistons, meansincluding said liner providing communication between said spaces, avalved inlet for a cooling fluid to one of said spaces and a valvedoutlet for the free flow of fluid from the other of said spaces awayfrom said communication, whereby a cooling fluid is drawn into saidspaces and said communication through said inlet on an outstroke of thepistons and is forced therefrom and caused to flow in one directionthrough said outlet on an instroke of the pistons.

3. In an internal combustion free piston en-' gine having a combustionchamber, spaces at opposite ends of said chamber, and pistons working insaid spaces, means forming a liner for the combustion chamber and apassage connecting said spaces, a check valve controlled inlet for acooling fluid to one of said spaces and a check valve controlled outletfor the free flow of fluid from the other of said spaces and saidpassage, whereby on an outstroke of the pistons fluid is drawn into saidspaces and passage through the inlet and on an instroke of the pistonsis forced 7. In aninternal combustion engine of the two chambercommunicating with said passage near the scavenging inlet, wherebycooling fluid is moved through said passage from the end near theexhaust to and out of the end near the scavenging inlet on both theexpansion and the contraction of said chambers.

8. In an internal combustion engine having a working cylinder with acombustion chamber therein, opposed working pistons in said cylinder,

means synchronizing the working pistons, and

from said spaces and passageand through said outlet.

4. In an internal combustion free piston engine having a. cylinder wallforming a combustion chamber, spaces at opposite ends ofsaid chamber andoppositely moving pistons in said spaces, said cylinder wall having aspace substantially around and lengthwise of its combustion chambersurface opening communication between said spaces, a check valvecontrolled inlet to one of said spaces for air under substantiallyatmospheric pressure and a check valve controlled outlet for the freeflow of air from said other spaces, whereby on an outstroke of thepistons fluid is drawn into said spaces from the inlet and on aninstroke of the pistons is forced from said spaces and through saidoutlet.

5. In an internal combustion free piston engine having a cylinder wallforming a combustion chamber, spaces at opposite ends of said chamber,and oppositely moving pistons in said spaces, means cooperating withsaid cylinder wall to form a substantially encircling passage from oneend to the other thereof which opens communication between said spaces,baflie fins on said wall within said passage, one of said spaces havinga check valve controlled inlet for cool low pressure air and the otherspace having a check valve controlled outlet for the free flow'of airaway from said passage, whereby on an outstroke of the pistons fluid isdrawn into said spaces and passage from the inlet and on an instroke ofthe. pistons is forced from said spaces and passage and through saidoutlet without a material heating compression of the air.

6. In an internal combustion engine means to cool the working cylinderthereof comprising means forming a passage around said cylinder fromend' to end thereof, two expansible and contractible chambers, one inconstant communication with each end of said passage, means to expandand contract the two chambers simultaneously, a check valve controlledinlet for cooling fluid into one only of said chambers and a check valvecontrolled outlet from the other of said chambers, whereby cooling fluidis moved through said passage from the chamber having the inlet to thechamber having the outlet both when the chambers expand and when theycontract.

a compressor cylinder at each end of the working cylinder with acompressing piston therein connected to and moving with the adjacentworking piston, means providing a cooling passage around the workingcylinder and in constantly free communication with both of saidcompressor cylinders, a check valve controlled inlet into one only ofsaid compressor cylinders and a check valve controlled outlet from theother only of said compressor cylinders, whereby cooling fluid is movedthrough said passage in the. same direction upon both the working andcompressing strokes of the working pistons.

9. In an internal combustion engine having a working cylinder with acombustion chamber, opposed working pistons in said cylinder, means tosynchronize said pistons, means providing an exhaust outlet at one endand a scavenging inlet at the other end of the combustion chamber,compressor cylinders at the ends of the working cylinder and a piston ineach compressor cylinder connected to and moving with the adjacentworking piston, means providing a cooling passage around the workingcylinder and constantly open into the compressor cylinder at itsopposite ends, a check valve controlled inlet into the compressorchamber at the exhaust end of the working cylinder and a check valve'controlled outlet from the compressor chamber at the scavenging end ofthe working cylinder,

whereby cooling fluid is moved through said passage from the compressorcylinder at the exhaust end to the compressor cylinder at the scavengingend on both the workingstroke and the compressing stroke of the workingpistons.

GEORGE A. MUELLER, JR. PAUL S. SHIRLEY.

REFERENCES CITED The following references are of record in the file ofthis patent:

